This invention relates to improvements in apparatus for and in methods of applying adhesive to web- or strip-shaped carriers, and more particularly to improvements in so-called pasters which can be utilized to apply one or more films of a suitable adhesive (such as hotmelt) to one side of a running substrate. Apparatus or pasters of such character can be utilized in filter or cigarette rod making and analogous machines to apply a film or coat of a suitable adhesive to one side (or to one marginal portion of one side) of a running web of cigarette paper, imitation cork or the like, or to a series of successive blanks (portions of a previously continuous web or strip) which can be converted into uniting bands in filter tipping machines, into tubular wrappers of continuous cigarette or filter rods, into discrete blanks for conversion into packets for cigarettes of the like, or for analogous purposes.
It is known to form an adhesive-coated strip- or web-shaped carrier from cigarette paper or the like by providing one side or one or more selected portions of one side of the carrier with one or more narrow strips or with a full coat or film of adhesive paste. The fully coated strip can be converted into discrete uniting bands which are utilized in a so-called tipping or filter tipping machine to connect filter rod sections of double unit legth with pairs of plain cigarettes of unit length. The thus obtained filter cigarettes of double unit length are thereupon halved to yield pairs of filter cigarettes of unit length.
It is also known to drape a continuous rod-like filler consisting of tobacco particles into a continuous cigarette paper web in such a way that one marginal portion of the resulting tubular envelope overlies and adheres to the other marginal portion. The application of adhesive to one marginal portion is carried out in or ahead of a so-called garniture wherein successive increments of the running web of wrapping material are caused to surround successive increments of the rod-shaped tobacco filler. The making of filter rod sections of unit length or multiple unit length is analogous; the main difference is that the material to be wrapped is a continuus rod (namely a converted tow) of filamentary filter material for tobacco smoke.
Filter tipping machines which employ webs or strips of so-called tipping paper, means for coating one side of the web with a film of adhesive, means for subdividing the adhesive-coated web into discrete uniting bands and for draping uniting bands around discrete filter rod sections and pairs of plain cigarettes are disclosed, for example, in commonly owned U.S. Pat. No. 4,901,860 granted Feb. 20, 1990 to Gunter Wahle et al. for "APPARATUS FOR TESTING AND CLASSIFYING CIGARETTES OR THE LIKE". Apparatus for converting a tow of filter material for tobacco smoke into filter rod sections or filter mouthpieces of desired length are disclosed, for example, in U.S. Pat. No. 3,974,007 granted Aug. 10, 1976 to Heinz Greve for "METHOD AND APPARATUS FOR THE PRODUCTION OF FILTER ROD SECTIONS OR THE LIKE". A cigarette making machine wherein one marginal portion at one side of a continuous running web of cigarette paper can be coated with adhesive upstream of a garniture is disclosed, for example, in commonly owned U.S. Pat. No. 4,721,119 granted Jan. 26, 1988 to Dieter Ludszeweit et al. for "ROD MAKING MACHINE WITH MEANS FOR ADJUSTING THE POSITION OF WRAPPING MATERIAL".
The viscosity of the film or films of adhesive paste remain at least substantially unchanged if the paster is operated continuously. However, the situation is different if the operation of the machine which processes adhesive-coated strips of cigarette paper, tipping paper or the like is arrested or slowed down because this entails substantial changes in the condition (particularly viscosity) of the adhesive in the paster. Thus, the volatile constituent(s) or ingredient(s) of the adhesive (a customary volatile ingredient is water) is or are likely to evaporate while (as is customary) the adhesive is caused to circulate during temporary stoppage of the processing machine or machines (such as the above enumerated filter rod making, filter tipping and cigarette rod making machine(s)). Continuous circulation or agitation of the adhesive is advisable because a mass of stagnant adhesive is likely to harden or to increase its viscosity to an extent which prevents adequate coating of a running web in response to renewed activation of the processing machine(s). However, even such continuous circulation does not prevent undesirable changes in viscosity of the adhesive paste because the volatile ingredient(s) of the adhesive is or are normally bound to escape at a rate which is sufficiently high to adversely influence the characteristics of the adhesive and necessitates segregation of long series of filter cigarettes when the processing machine(s) is or are restarted or accelerated from less than full speed to normal operating speed.
In the absence of any undertakings to the contrary, even short-lasting or extremely short-lasting accelerations of a filter tipping, cigarette rod making or other machine while the adhesive is less than fully satisfactory invariably results in the making of long series of defective plain cigarettes, filter cigarettes or analogous products because a modern high-speed machine of such character can turn out up to and even in excess of 15,000 rod-shaped articles per minute.